1. Field of the Invention
This invention relates to a process for deodorizing garlic or Welsh onion for removing or reducing the especially bad odor of garlic and Welsh onion and the like without damaging their characteristic odor, bitter taste and nutrition.
2. Description of the Prior Art
The usual types of Welsh onions can be roughly classified as long neck Welsh onion, common onion and leek. The Welsh onion (botanical name: Allium fistulosum) is roughly classified as A.f. var. Caespitosum and A.f. var. viviparum. The common onion (botanical name: Allium Cepa) is classified as plain onion as well as tomato onion, potato onion, multiplier onion, (A.C. form proliferum) and top onion or the like. The leek (botanical name: Allium taberosum), is classified as a scallion (a large leek, a plain leek)=(Allium bakeri) or the like. Garlic (botanical name: Allium sativum forme pekinense), includes A. Scorodoprasum and Allium Grayi or the like. These garlics and Welsh onions have been used as tonic foods and have long been used as materials essential for certain recipes such as soup or the like. However, these garlics and Welsh onions have a unique bad odor during cooking or as an oral odor or a body odor after partaking of a meal, so that the odor is considered to be a disadvantage in social life. Various resolving processes (an odor removing and a deodorizing process) have been applied to garlic. However, although it has not been possible to find a deodorizing process for Welsh onions such as the common onion or long neck Welsh onion, there are many dishes prepared with common onions as compared with those using other Welsh onions or garlic and there are many people who do not eat these dishes due to their residual odor. In particular, the odor of the common onion is one of the troublesome problems in children's eating habits. In addition, it is already pointed out that if the pungent taste and bitter taste of the common onion are removed, the dishes become more delicious and many cooks are looking for a method for removing the pungent taste and odor of the common onion.
With the object of meeting the aforesaid requirement, the present inventor has carried out research for 20 years so as to restrict the bad odor or bitter taste of garlic or Welsh onion or the like. It was found that the bad odor component comprises several kinds of allyl sulfides, i.e. diallyl sulfide, allyl disulfide, allyl trisulfide and allyl propyl disulfide. These are decomposed by the action of an inner alkali and then they are changed into disulfides and sulfide dioxides and gasified. Fragrance substances contained in garlic and Welsh onion and the like (a so-called nice odor producing a delicious flavor in cooking) are confirmed to be citral, geraniol, linalool, alpha-phellandrene and beta-phellandrene or the like having boiling points of 171.degree. C. to 230.degree. C. In addition, the bitter taste component is an alkaloid which is called quinovatine. Although quinovatine is present in all botanical plants as an organic acid, it has the characteristic that when it is reacted with acid to make a salt, it then becomes water soluble. In turn, when alliin contained in garlic and Welsh onion or the like is decomposed under the action of the enzyme alliinase, aricine, ammonia and pyruvic acid are generated. Aricine and pyruvic acid have a certain tonic action. In view of these facts, the present invention has as its object to provide a deodorizing process for garlic and Welsh onion or the like in which the bad odor generating substance contained therein can be efficiently reduced. A small amount of the characteristic odor contained in garlic or Welsh onion or the like is maintained when the garlic or Welsh onion is eaten, and after eating it is not noticed as an oral odor and body odor, its bitter taste is restricted and its fragrance or nutrition remains unchanged.